I just went to an almost 5 year old and she ended up riding almost everything her height would allow. She had been there when she was 3 and we were anticipating that she's like some of the "bigger" rides this time, but we weren't really sure how much (she had kind of a mixed reaction when she went to a local theme park with kid's roller coasters). We started "small" (Goofy's Sky School) and worked up to Space Mountain. Of the ones she could ride, we skipped Matterhorn (forgot about it in truth), ToT, and HM. We also skipped Screamin' and Indy, but she didn't make the height requirement for those, otherwise she probably would have tried Screamin' (not sure about Indy).
Her favorite "thrill" rides were RSR (by far, this was her favorite), Goofy's Sky School, Big Thunder, Star Tours, and Splash Mtn. Her favorite "non-thrill" rides were Storybook Canal Boats, Casey Jr, Little Mermaid, and every character meet and greet we could find.